I kind of remember Dr. Fred saying to use an eraser!  It is also in his poultice guide!  Or next option is to make a poultice with de-natured alcohol and poultice powder! 

--- On Thu, 2/26/09, Zev Guez <zev@stonerestorationplus.com> wrote:
From: Zev Guez <zev@stonerestorationplus.com>
Subject: [sccpartners] Pencil marks
To: "Restoration and Maintenance" <sccpartners@stoneandtilepros.com>
Date: Thursday, February 26, 2009, 8:01 PM

Hi How would you remove pencil marks from a white thassos marble. The installers marked them and they wont wipe off with cleaners. Thanks in advance for all your help.

--
Zev Guez
Stone Restoration Plus
(732) 309-3878
www.stonerestorationplus.com